Conventionally, a variable displacement swash plate type compressor (hereinafter, simply referred to as “compressor”) described in Japanese Patent Laid-Open No. 2006-207464 is known. The compressor includes a housing, a swash plate, a plurality of pistons, a suction passage, and a displacement control valve. The housing has a suction chamber, a plurality of cylinder bores, a crank chamber and a discharge chamber. The swash plate is provided in the crank chamber, and an inclination angle of the swash plate is changed depending on a crank chamber pressure in the crank chamber. The piston is accommodated in the cylinder bore, and forms a compression chamber between the piston and the housing. Further, the piston reciprocates in the cylinder bore with a stroke corresponding to the inclination angle. In this manner, the piston sucks refrigerant in the suction chamber into the compression chamber, compresses the refrigerant in the compression chamber, and discharges high-pressure refrigerant to the discharge chamber from the compression chamber. The suction passage connects the outside to the suction chamber. The displacement control valve is capable of changing the crank chamber pressure.
To be more specific, the compressor has: a first supply passage which makes the discharge chamber and the displacement control valve communicate with each other; a second supply passage which connects the displacement control valve to the crank chamber; and a bleed passage which connects the crank chamber to the suction chamber. The displacement control valve regulates a communicating area between the first supply passage and the second supply passage. The compressor further includes an opening degree regulating valve. The opening degree regulating valve is provided in a valve accommodation chamber which is formed in the housing, communicates with the outside, and extends in the radial direction. The opening degree regulating valve has a valve chamber which has an inlet port opening to the outside, and extends in the radial direction. A suction communication hole which communicates with the suction chamber, and has a communication port opening to the valve chamber; a bleed communication hole which communicates with the crank chamber, and has a bleed port opening to the valve chamber; and a control communication hole which communicates with the second supply passage, and has a control port opening to the valve chamber are formed in the housing. A first valve body and a second valve body which are movable in the radial direction, and a bias spring which connects the first valve body to the second valve body are accommodated in the valve chamber. The first valve body and the second valve body move in the radial direction due to a differential pressure between a suction pressure of the refrigerant before the refrigerant is sucked into the suction chamber and a crank chamber pressure.
In this compressor, when the differential pressure between the suction pressure and the crank chamber pressure increases, the first valve body reduces an opening degree of the suction passage, and the second valve body reduces an opening degree of the bleed passage. On the other hand, when the differential pressure between the suction pressure and the crank chamber pressure decreases, the first valve body increases the opening degree of the suction passage, and the second valve body increases the opening degree of the bleed passage. Thus, in this compressor, while pressure loss of the suction pressure at a high displacement is prevented, pressure variation in the suction pressure at a low displacement is minimized, so that quiet is ensured.
However, in the above-mentioned conventional compressor, volumetric efficiency at the low displacement is insufficient, and at the time of startup, it is difficult to rapidly drain liquid refrigerant or the like which may be filled in the crank chamber, so that the displacement is difficult to be rapidly increased.
That is, in this compressor, the second valve body of the opening degree regulating valve cannot close the bleed passage, and at the low displacement, the compression phase is performed again by draining the high-pressure refrigerant in the crank chamber to the suction chamber and hence, volumetric efficiency is insufficient. Accordingly, when an opening area of the bleed passage is set small, the liquid refrigerant or the like which may be filled in the crank chamber cannot be rapidly drained to the suction chamber at the time of startup, so that it is difficult to rapidly increase the displacement.
Accordingly, in order to ensure sufficient volumetric efficiency at the low capacity, and also to allow the liquid refrigerant or the like to be rapidly drained to the suction chamber at the time of startup, it may be considered a technique where, while the opening area of the bleed passage is set large, a separate bleed valve is used which can change the opening area of the bleed passage, as described in Japanese Patent Laid-Open No. 2011-185138, for example. In this case, it is considered that, by allowing the bleed valve to release the opening area of the bleed passage at the time of startup, the liquid refrigerant or the like can be rapidly drained to the suction chamber at the time of startup, so that the displacement can be rapidly and easily increased. It is also considered that, by allowing the bleed valve to close the opening area of the bleed passage at the low displacement, the high-pressure refrigerant in the crank chamber is not compressed again and hence, volumetric efficiency is increased.
However, with the use of such a separate bleed valve, the parts count is increased thus causing an increase in manufacturing cost and reduction of design flexibility.
The present invention has been made in the light of the conventional circumstances described above, and an object of the invention is to provide a variable displacement swash plate type compressor capable of solving all of the following tasks.
(1) While pressure loss of a suction pressure at a high displacement can be prevented, quiet at a low displacement can be also ensured.
(2) High volumetric efficiency at the low displacement can be realized without causing an increase in manufacturing cost and reduction of design flexibility.
(3) Liquid refrigerant or the like which may be filled in a crank chamber can be rapidly drained at the time of startup, so that the displacement can be rapidly increased.
A compressor according to the present invention includes:
a housing having a suction chamber, a cylinder bore, a crank chamber, and a discharge chamber;
a swash plate provided in the crank chamber, an inclination angle of the swash plate being changed depending on a crank chamber pressure in the crank chamber;
a piston accommodated in the cylinder bore and forming a compression chamber between the piston and the housing, the piston that sucks refrigerant in the suction chamber into the compression chamber, compresses the refrigerant in the compression chamber, and discharges the high-pressure refrigerant to the discharge chamber from the compression chamber by reciprocating in the cylinder bore with a stroke corresponding to the inclination angle; and
a displacement control valve provided in the housing, and being capable of changing the crank chamber pressure,
wherein a suction passage that connects the outside to the suction chamber, a first supply passage that makes the discharge chamber and the displacement control valve communicate with each other, a second supply passage that connects the displacement control valve to the crank chamber, and a bleed passage that connects the crank chamber to the suction chamber are formed in the housing,
a valve chamber that has an inlet port opening to the outside and extends in a first direction, a suction communication hole that communicates with the suction chamber and has a communication port opening to the valve chamber, a bleed communication hole that communicates with the crank chamber and has a bleed port opening to the valve chamber, and a control communication hole that communicates with the second supply passage and has a control port opening to the valve chamber are formed in the housing,
a first valve body that is movable in the first direction and changes an opening area of the communication port, a second valve body that is movable in the first direction and changes an opening area of the bleed port, and a bias spring that connects the first valve body to the second valve body are accommodated in the valve chamber,
when a suction pressure of the refrigerant being taken into the suction chamber is lower than a set suction pressure, and the crank chamber pressure is higher than a control pressure in the second supply passage, the first valve body is configured to reduce an opening degree of the suction passage, and the second valve body is configured to open the bleed passage,
when the suction pressure is higher than the set suction pressure, and the crank chamber pressure is higher than the control pressure, the first valve body is configured to increase the opening degree of the suction passage, and the second valve body is configured to open the bleed passage, and
when the crank chamber pressure is lower than the control pressure, the first valve body is configured to reduce the opening degree of the suction passage, and the second valve body is configured to close the bleed passage.
Other aspects and advantages of the invention will be apparent from embodiments disclosed in the attached drawings, illustrations exemplified therein, and the concept of the invention.